This patent relates to a twist-lock valve for use with a fluid dispensing cartridge. More particularly, this patent relates to a lithographic printing press ink cartridge valve that can be adjusted to dispense inks of varying viscosities.
Modern ink cartridges for printing presses typically comprise a hollow tubular body, a moveable plunger inserted into one end, and a stationary dispensing fitment attached to the opposite end. The dispensing fitment covers the dispensing end of the tubular body and also serves as a valve for opening and closing the cartridge. Ink is extruded from the cartridge when the plunger is forced toward the dispensing end either manually or, more commonly, by pneumatic pressure.
The valve or dispensing fitment is mounted in sealing engagement within the dispensing (bottom) end of the tubular body. The valve serves four functions: (1) it controls the flow of ink from the cartridge when the plunger is activated; (2) it prevents the flow of ink at all other times, including during filling, transportation, storage, and installation of the cartridge on the printing press; (3) it prevents the introduction of air into the cartridge, which can cause localized ink drying at the nozzle and can effect the properties of the ink contents through oxidation or changes in viscosity; and (4) it prevents the flow of ink to other areas of the dispensing fitment or printing equipment. (Ink found in these areas can dry and flake off, contaminating the ink reservoir.)
Commonly owned U.S. Pat. No. 6,547,108, incorporated herein by reference, is directed to a pressure-activated flexible valve for an ink cartridge. The valve has a single sealing surface and comprises an inner component having a dish-shaped valve seat and an outer component having an annular rim that abuts the valve seat when the valve is closed. In a key aspect of the invention, the outer component also has an annular flexible portion configured to flex upward and outward when subjected to sufficient pressure from the container fluid material, thereby moving the annular rim between a closed position and an open position.
While this valve is suitable for its intended purpose, it cannot be used with all types of inks, including highly viscous ink. It can be difficult to extrude highly viscous inks through the relatively narrow annular opening between the valve rim and seat. The valve can also result in limited flow when used with a pneumatic hand-gun.
One possible solution to these problems is for the user to stock multiple cartridges for use in different applications and with inks of different viscosities. But this solution requires additional storage space and can result in increased printing costs.
What is needed is a single adjustable valve that is capable of dispensing a variety of inks under a variety of applications, including inks having different viscosities. The present invention fulfills this need.
It is an object of the present invention to provide a pressure-activated fluid dispensing valve that can be used with fluids of different viscosities.
Yet another object of the present invention is to provide a pressure-activated valve that can be set to a position that does not allow any flow of ink from the container.
Still another object of the present invention is to provide an ink cartridge that can dispense inks having very high and low viscosities.
Another object of the present invention is to provide an ink cartridge that works well with both automatic ink dispensing equipment hand dispensers.
Further and additional objects will appear from the description, accompanying drawings, and appended claims.